Quality improvement and mechanism analysis of non-rinsing tilapia surimi gel

Non-rinsing surimi has better flavor due to its higher protein and fat content, but it has insufficient gel properties. We investigated the effects of starch, hydrophilic colloid and dietary fiber on the texture characteristics, rheological properties, color, water holding capacity and cooking loss rate of tilapia non-rinsing surimi. Besides, we analyzed the mechanism of gel quality enhancement of non-rinsing surimi gel from the aspects of water distribution, intermolecular force and protein structure. The results show that compared with the control group, the starch, hydrophilic colloid, dietary fiber and other substances could improve the texture characteristics and gel strength of non-rinsing surimi. The water holding capacity of surimi increased and the cooking loss rate decreased. Under the influence of starch, hydrophilic colloid and dietary fiber, the free water in non-rinsing surimi was converted into immobilized water and bound water, the hydrophobic interaction between protein molecules enhanced, and the α-helix was transformed into ordered β-sheet. The formation of dense and stable surimi gel network structure could significantly improve the gel quality of non-rinsing surimi. Especially, the optimized compound addition (1.5% hydroxypropyl distarch phosphate, 0.3% sodium polyacrylate, 12% corn starch and 1.5% seaweed dietary fiber) had the most significant effect on surimi gel.